Finding new methods

When it comes to reducing and repurposing waste, companies are looking beyond traditional recycling methods to find ways byproducts can become new products.

Thomas Dalsgaard, Executive Vice President at REnescience

Denmark’s REnescience A/S has developed a waste-treatment system that could reduce or eliminate the need to separate waste before it is processed.

“Today’s waste handling systems often rely on impractical methods for separating our municipal solid waste (MSW): they require every single household to sort waste into different bins for organic and inorganic waste and for waste collectors to transport these different waste streams separately,” said REnescience’s Executive Vice President Thomas Dalsgaard. The company is a spin-off of DONG Energy’s research and development work on pre-treatment of biomass for energy purposes, which also includes Inbicon A/S, a subsidiary working on commercialising second generation bioethanol.

REnescience’s long-term goal is to supply the world with a new clean technology that could turn more than 95 percent of the biodegradable material contained in mixed municipal solid waste into a “bio-liquid.” “This liquid is highly-suited for biogas production and a host of other things, including second-generation bioethanol,” Dalsgaard noted.

By applying enzymes, REnescience is able to separate organic from inorganic waste. “ The process liquefies organic material contained in the unsorted MSW, thereby enabling biogas production from the biological contents of our waste,” explained Dalsgaard. The remaining solid part of the waste containing glass, PVC and metals can be recycled. A tiny portion of the residue comprised of textiles, woody materials and low-grade plastics can serve as fuel in high-efficiency energy production. To help deploy the company’s technology more quickly than it could on its own, REnescience currently has entered a research and development collaboration with the Danish company, Amagerforbrændingen, where a REnescience demonstration plant is handling waste.

In Sweden, Chemrec is finding a better use for the liquid biomass that is the residue from the chemical processes at paper mills which today is disposed of with low value add. The company’s gasification technology converts the material, known as “black liquor,” into a biofuel. Sweden could reduce 10 percent of its total CO2 emissions by adopting this new recycling technology, according to Chemrec. The company has earned a “most promising” rating in the Cleantech Top 100, a global ranking.

If all of the nation’s pulp mills used the gasification process, enough biomethanol and “bioDME” fuel could be produced to provide 50 percent of the fuels for all heavy transport vehicles in Sweden, said company CEO Max Jönsson. “One pulp mill could power 5,000 heavy-duty trucks.”

The gasification technology can produce many different fuels, including synthetic gasoline, FT diesel, gaseous diesel (DME) and methanol. Chemrec’s development plant is located at the Smurfit Kappa Mill in Piteå and it is producing BioDME to fuel Volvo heavy trucks.

Some vehicles do need minor modifications to use biofuel. While DME’s properties are similar to liquid petroleum gas, some adjustments are necessary for truck engine injection systems and fuel tanks. The cost of this is offset by less extensive exhaust system, because the fuel has virtually no particulate emissions. Chemrec also can produce drop-in fuels, which do not require adjustments to engines.

The idea for Chemrec’s gasification process goes back to the mid-1980s, when some engineers working on the gasification of coal and oil who also had pulp and paper industry experience, proposed gasifying the black liquor because it had similar properties to certain heavy oils. “This was exciting because it is liquid and is actually more reactive than oil, coal and woody biomass. It is also derived from forest residue and available industrially at the pulp mills,” according to Jönsson. “Black liquor therefore solves known deal-breakers such as feeding the biomass into the reactor, ensuring good conversion to end product and synergies with existing forestry value chains. Bottom line is high efficiency, avoided investment, high CO2 saving and no competition with food production. It is the only biomass which is competitive while not being food-competing,” Jönsson added.

Among the pluses of Chemrec’s system is that it is able to efficiently utilize existing materials and facilities. Black liquor has a very high yield on incremental biomass of up to 70 percent; Chemrec is able to work with existing sites, utilities, procurement and logistics; and most pulp mills can use the technology, according to Jönsson.
Based on the investment intensity and efficiency in a 2006 Princeton study by Erik D Larsen “A Cost-Benefit Assessment of Gasification-Based Biorefining in the Kraft Pulp and Paper Industry”, black liquor gasification is one of very few technologies that offers the potential to be competitive without subsidies.

So more biofuel could soon be on the way. Chemrec officials are in discussions with a large number of pulp companies and are engaged in about half a dozen active studies or projects, including ones at Domsjoe and Vallvik.